(1) Field of the Invention
The present invention relates to group III-V compound semiconductor high brightness white or desire color light emitting diodes (LEDs).
(2) Prior Art
Extensive efforts have been devoted to develop white LEDs and white LED assemblies, including (1) using wavelength converter materials including fluorescent materials, phonton-recycling semiconductors, and dye; (2) integrating red, green, and blue LEDs (RGB LEDs) into a LED lamp (3) stacking two LED chips of different wavelengths; and (4) growing more than one active layers emitting lights of different wavelengths on a substrate patents for this method include U.S. Pat. Appl. No. 20030173573, by Udagawa, U.S. Pat. No. 6,649,943 by Shibata, et al., and U.S. Pat. No. 6,163,038, by Chen, et al.
Several different material systems including GaInPN, GaInN, and GaPN for emitting white light are disclosed in above patents. A common practice for generating white light is to combine blue and yellow lights. In order to have the same chromaticity coordinate as illuminant D.sub.65, the complementary wavelengths and power ratio of two complementary monochromatic lights are required to satisfy the following relation:
Complementary wavelengths:LambdaPower ratioLambda.sub.1Lambda.sub.2P(Lambda.sub.2)/P(Lambda.sub.1)430 nm562 nm1.4440 nm563 nm1.8450 nm564 nm1.8460 nm566 nm1.5470 nm570 nm1.1
The above disclosed material systems do not emit yellow light as bright as that of the material system (AlGa)InP. Therefore to be able to emit white light from the LEDs of those material systems, the intensity of blue light needs to be dimmed. So the existing white LEDs with above mentioned material systems do not have high brightness. Therefore there is a need for high brightness white or desire color LEDs.